The principal overall objectives are to elucidate the ecology of the dengue viruses and related arboviruses in Malaysia, with special reference to the jungle cycles; and to establish the importance of dengue as a zoonosis involving primates. Continuing and modified field studies and laboratory transmission experiments will be conducted in an effort to establish what mosquito species is the important jungle canopy vector. An effort will be made to gather evidence linking dengue activity in jungle, rural, and town habitats and to assess the true roles of the known vectors in various habitats in relation to disease in man. A variety of tested collecting methods will be employed. Laboratory studies will include isolation, characterization, and identification of viruses utilizing mice, cell cultures, and parental inoculation of mosquitoes, and detailed serology using microtiter techniques and plaque reduction tests.